CVE-2024-44956 Information

Description

In the Linux kernel the following vulnerability has been resolved:

drm/xe/preempt_fence: enlarge the fence critical section

It is really easy to introduce subtle deadlocks in preempt_fence_work_func() since we operate on single global ordered-wq for signalling our preempt fences behind the scenes so even though we signal a particular fence everything in the callback should be in the fence critical section since blocking in the callback will prevent other published fences from signalling. If we enlarge the fence critical section to cover the entire callback then lockdep should be able to understand this better and complain if we grab a sensitive lock like vm->lock which is also held when waiting on preempt fences.

Reference

https://git.kernel.org/stable/c/458bb83119dfee5d14c677f7846dd9363817006f https://git.kernel.org/stable/c/3cd1585e57908b6efcd967465ef7685f40b2a294